This invention relates to an exhaust gas control means, and more particularly, to an exhaust gas control means for vehicles such as motorcycles.
It is well known that the design of the exhaust system for an internal combustion engine can significantly affect the engine performance. With multiple cylinder engines, it is a practice to employ individual exhaust pipes that extend from the individual exhaust ports of the engine and which merge into a common expansion or collector chamber for improving top end performance. Although the use of an expansion or collector chamber for this purpose is effective increasing maximum output of the engine, it has been found that the chamber can contribute to poor running under other than maximum speed conditions. This is a result of the reflection of the exhaust gas pulses from one cylinder back to another cylinder during these running conditions. These pulsations transferred back into the exhaust parts of another cylinder tend to reduce the breathing ability of the engine at lower running speeds and, as noted, adversely affects the output of the engine.
In order to improve the efficiency of the engine and its output at all running conditions, it has been proposed to incorporate a reflective valve means in the individual exhaust pipes upstream of the expansion or collector chamber. Such an arrangement is shown in the co-pending applications entitled "High Performance Exhaust System for Internal Combustion Engine", by Hideaki Ueda, Ser. No. 935,340, filed Nov. 26, 1986, and "High Performance Exhaust System For Internal Combustion Engine", by Hideaki Ueda, Ser. No. 935,342, filed Nov. 26, 1986, and assigned to the assignee of this application.
Although the systems disclosed in those applications are particularly effective in improving the performance throughout the entire engine and loads ranges, the positioning of the valves in the exhaust pipe is important to the effectiveness of the system and frequently the valves must be positioned directly underneath the engine. In such an arrangement, this can cause difficulty with certain types of vehicles, particularly compact vehicles such as motorcycles. Specifically, where the engine exhaust pipes pass beneath the crankcase transmission of the vehicle, they can seriously reduce the ground clearance and/or may be positioned so that they interfere with leaning of the machine when cornering.
It is, therefore, a principal object of this invention to provide an improved and compact exhaust gas control arrangement for vehicles.
It is a further object of this invention to provide an improved and compact motorcycle arrangement having an exhaust gas control arrangement.
In connection with the use of such exhaust control valves, it is obvious that heat can be a significant problem. In order to provide a valve that is effective, it is desirable to minimize the amount of heat which is exerted on the valve so as to ensure long life and good operation.
It is, therefore, a further object of this invention to provide an improved arrangement for exhaust gas control wherein the control means is effectively cooled.
It is a further object of the invention to provide an exhaust gas control arrangement for a motorcycle wherein the control valve will be adequately cooled.
In connection with the use of control valves for multiple cylinder engines, it is desirable to maintain the valve shafts as short as possible so as to minimize the effect of thermal expansion. One way this can be done is by having the exhaust pipes and the individual valves positioned vertically above each other. However, such a configuration can further aggravate the ground clearance problems already noted.
It is, therefore, a still further object of this invention to provide an exhaust gas control valve arrangement which will permit a compact configuration and, at the same time, minimize the effects of thermal expansion.
It is another object of the invention to provide a compact multiple valve element control valve for an engine exhaust system.
In connection with vehicles wherein the control valve is positioned at a low point in the vehicle, it is essential to ensure that the valve will not be struck by obstacles when the vehicle is in motion. If the valve becomes struck, there is a danger that it may be damaged and/or locked in a position which will not result in good performance under all running conditions.
It is, therefore, still a further object of this invention to provide an improved and protected exhaust gas control means for a vehicle.